williams



Jan. 24, 1956 H. L. WILLIAMS 2,732,055

TYPEWRITEZR PLATEN LOCKING DEVICE Filed June 5, 1953 2 Sheets-Sheet l 25I? -30 42 2'6 \WE How/m0 L M/ILL/AMJ INVENTOR.

J n- 24, 1 H. L. WILLIAMS TYPEWRITER PLATEN LOCKING DEVICE 2Sheets-Sheet 2 Filed June 5, 1953 How/m0 L M/llL/AMS IN VEN TOR.

United States P ent TYPEWRITER PLATEN LOCKING DEVICE Howard L. Williams,Wichita, Kans.

Application June 5, 1953, Serial No. 359,927

4 Claims. (Cl. 197-141) This invention relates to an improved device forautomatically locking the platen of a typewriter or other lineby-linerecord making machine, thus making it impossible for the machineoperator to accidentally type too near the bottom of the sheet.

The primary disadvantage of previous devices. of this type has been thedifficulty in releasing the locked platen to remove the paper from themachine, as well as the difiiculty of resetting the device so that a newsheet of paper can be positioned in the machine.

It is an important object of this invention to provide a platen lockingdevice the working parts of which are enclosed in a small cylindricalhousing which replaces one of the conventional hand knobs at one end ofthe typewriter platen, the housing thereafter serving in place of theconventional knob.

It is a prime object to provide a device of this type which is easilyreleased, after it has locked the platen, by simply manually rotatingthe knob-like housing in the direction normally required to releasepaper from the typewriter, no outward pull on the knob being required,and no resetting of stop pins being required for the insertion of a newsheet of paper in the machine.

It is an additional object to provide a device of this type Which can bemanufactured as an attachment for typewriters and other record makingmachines presently in use, or which can be installed at the factory asan integral part of the machine without requiring design changes. Whensold as an attachment, the device requires anchorage to the typewriterframe with only two small metal screws.

An additional object is to provide a platen locking device which caneasily be set by the operator to lock to preserve a margin of desiredlength at the bottom of the sheet, whether the sheet is a conventionaleleven inches in length, or is 14 inches in length.

The invention, together with other objects, will be more clearlyunderstood when the following description is read in connection with theaccompanying drawings, in which:

Fig. 1 is a central sectional view through a locking device embodying myinvention, installed on the shaft of a typewriter platen, and on thetypewriter frame, the platen and frame being shown fragmentarily;

Fig. 2 is a perspective view of a completely assembled platen lockingunit embodying this invention;

Figs. 3, 4, 5, 6, and 7 are transverse sectional views takenrespectively along the lines 3-3, 4-4, 5-5, 6-6, and 7-7 of Fig. l, andshow details of construction.

Fig. 8 is a fragmentary side elevation of a stub shaft, which is a partof the invention;

Fig. 9 is a sectional view of a modified form of the invention mountedon one end of a typewriter platen;

Fig. 10 is a sectional view taken along the line 10-10 of Fig. 9, andshows a modified form of a grooved plate which is a part of theinvention; 7 l

Fig. 11 is a perspective view of-a portion-only of the 2,732,055Patented Jan. 24, 1956 modified form of the invention, and shows detailsof construction and assembly;

Fig. 12 is a side elevation of a stop element, with parts in section;

Fig. 13 is a transverse sectional view taken along the line 13-13 ofFig. 12; and

Fig. 14 is a sectional view similar to Fig. l with parts omitted andparts distorted in proportion for clarity.

Generally, the invention includes a disc fixed to rotate with thetypewriter platen, and having one of its side faces spirally grooved; aresilient traveler fixed to the ,typewriter frame and projecting intothe spiral groove to travel therein as the platen rotates, and to stopplaten rotation when the traveler reaches the end of the spiral groove;a housing for such mechanism in the form of a platen control knob; andmechanism connecting the knob and the spirally grooved disc to releasethe traveler from the spiral groove in the disc when the knob is turnedin a direction to remove the paper from the typewriter.

Detailed description The invention includes an assembly supporting stubshaft 15 secured coaxially on one end of the platen 16. This shaft isrotatable in a plate 17 which is secured to the typewriter frame 18 bymeans of a screw 19. Stub shaft 15 is locked to rotate with platen shaft20 by means of a set screw 21.

As clearly shown in Fig. 3, the outer face of plate 17 is machined toprovide a recess 22 for receiving and seating a coil spring 23, theouter end 24 of which projects outwardly at right angles, as in Fig. 1,and serves as a groove follower and stop. its path of travel isindicated by the broken lines in Figs. 3 and 4. The spring 23 is held inposition in its recess 22 by a thin sheet metal plate 25, which issecured to plate 17 by means of screws 26, the plate 25 having a slot 27to provide free movement for follower 24.

Shaft 15 carries a plate 28, the inner surface of which is provided witha shallow spiral groove 29, which is adapted to receive and guide theouter end of follower 24. On its outer surface, plate 28 has an integralcentrally bored boss 30 the bore of which journals the hub of a plateretracting member 31, which is rotatable on shaft 15. A pair of matingsemi-circular angle section retainers 32 and 33 (Figs. 1, 6, and 7) havetheir semiannular side flanges seated in an annular groove 34 in thejournaled hub of member 31. The retainers are held in position on boss30 by screws 35, 36, 37 and 38. This type of connection permits relativerotation between the plate 28 and the member 31, while preventingrelative axial movement. A coil spring 39 bears against the disc end ofmember 31 and against an integral head 40 carried by the outer end ofshaft 15. Spring 39 thus serves to normally maintain the spirallygrooved surface of plate 28 against the adjacent surface of plate 25, tothus maintain the end of follower 24 in the spiral groove 29.

A cup-like platen knob 41 slips over the outer end of the describedassembly as a housing, and its inner end is secured to the periphery ofthe disc end of member 31 by means of spaced countersunk screws 42 and43.

Knob 41 is indirectly and operably connected to plate 28 through plateretracting member 31, a pair of diametrically opposite left hand spiralgrooves 74 and 75 in shaft 15, cooperating internal diametricallyopposite recesses 76 and 77 in the hub of member 31, and steel balls 78and 79 seated in said grooves and recesses, as more clearly shown inFig. 14. In addition, the connecting and plate operating means includesa pair of diametrically opposite right hand spiral grooves 44 'and 45 inshaft 15, cooperating substantially quarter-spherical recesses 80 and 81in plate 28, cooperating internal circumferentially extending grooves48'--and"49 (also see Fig. 6) in the hub of member 31, and steel balls46 and 47 seated in the last mentioned grooves and recesses. As shown,grooves 48 and 4-9 are quarter-spherical in cross section and extendcircumferentially through an arc of approximately 90 (Fig. 6). Normallythe spring 39 maintains the respective mentioned parts in the relativepositions shown in Figs. 1, 6, and 14, with the balls seated at theinner ends of the spiral grooves 44, 45, 74 and 75, respectively, andthe retracting member 31 at the limit of its counterclockwise travelwith relation to the shaft and plate 28. The purpose of: the dcscribedconnecting mechanism is to simultaneously move the plate 28counterclockwise slightly and axially outward on shaft 15 and away fromgroove follower 24 as a result of normal clockwise movement of knob 41to remove paper from the typewriter. Such movement of plate 28 freesfollower 24 from its groove 29, and allows the follower to return to itsnormal starting position near the outer end of groove 29.

Operation When clockwise torque is applied directly to shaft 15 byplaten shaft 20, as a result of typing, plate 28 is forced to rotatewith shaft 15, the force being transmitted from the inner ends ofgrooves 74 and 75 to balls 73 and 79, to plate retracting member 31, andsimultaneously from the side edges of the spiral grooves 44 and to balls46 and 47, and thence to the walls of the recesses 80 and 81 in plate28. This direct application of clockwise torque thus acts on plate 28just as if the plate were directly connected to the shaft. During thisrotation of plate 28, groove follower 24 follows spiral groove 29. Aftera predetermined number of revolutions of the platen 16, depending on thediameter thereof and the length of the paper being used in thetypewriter, fol lower 24 reaches the inner end of the spiral groove 29,and the end of this groove, together with the instant immobility offollower 24, prevent further rotation of the platen, thus arresting themovement of the sheet of paper in the typewriter. By making the groove29 the proper length, considering the circumference of the platen andthe length of the sheet of paper being used, this locking of the platenoccurs when the last line of typing on the sheet of paper is a desireddistance from the bottom edge of the sheet.

To release the platen to permit removal of the typed sheet from thetypewriter, it is only necessary to grasp knob 41 and to rotate itmanually in a clockwise direction. A slight rotation of the knob 41accomplishes this release, without any need whatever for pulling outwardon the knob. Due to the fact that shaft 15 is at the moment lockedagainst clockwise rotation, clockwise rotation of knob 41 withconsequent clockwise rotation of plate retracting member 31 causes balls'78 and 79 to move toward the respective outer ends of helical grooves74 and 75. This movement causes plate retracting member 31 to moveaxially outward on shaft 15. Retainers 32 and 33 cause plate 28 to moveaxially outward on shaft 15 along with the retracting member 31.Simultaneously balls 46 and 47 are forced to move toward the respectiveouter ends of their spiral grooves 44 and 45, and since these lastmentioned grooves spiral counterclockwise, the plate 28 issimultaneously forced to partially revolve counterclockwise. Thiscounterclockwise movement of the plate 28 breaks contact between theextreme end 50 of spiral groove 29 and the groove follower 24. The axialoutward movement of plate 28 completely frees the follower 24 from thesidewalls of groove 29, and permits follower 24 to return to its normalposition, as shown in Figs. 3 and 4.

As soon as groove follower 24 is disengaged from spiral groove 29, shaft15 is again free to rotate clockwise. Continued clockwise movement ofknob 41 forces shaft 15 to rotate clockwise, motion being againtransmitted through the balls 78 and 79 and their respective grooves 74and 75. Almost simultaneous with the release of groove follower 24 fromgroove 29, due to outward plate movement, coil spring 39 again returnsthe various parts to their respective normal positions, as shown inFigs. 1 and 14. Continued clockwise movement of knob 41 naturally freesthe lower edge of the sheet of paper from the typewriter.

As is clearly shown in Fig. 2, fixed plate 17 is provided with aperipheral mark 51, and rotatable plate 28 is provided with spacedperipheral marks 52, 53, and 54, adapted to selectively register withmark 51. The three marks on plate 28 serve to orient plate 28 and itsgroove 29 with relation to the stop 24, to thus control the point atwhich the lengthwise travel of the typing paper is arrested, thuscontrolling the spacing of the last permitted line of typing from thebottom edge of the sheet.

For instance, if knob 41 is adjusted by the operator to cause mark 52 toregister with mark 51, and a sheet of paper is inserted into thetypewriter with the plate 28 and the platen in the relative positionsthus established, the platen will be permitted to travel fartherrotationally than if the paper had been inserted into the machine withthe marks 54 and 51 in register. Consequently, the paper will bepermitted to travel a greater lengthwise distance as the platen rotates,and the last permitted line of typing on the sheet will appear nearerthe lower edge of the sheet than if the paper had been inserted into themachine with the marks 54 and 51 in register. By thus varying theposition of knob 41 just prior to insertion of the paper into thetypewriter, the operator can predetermine the location of the lastpermitted line of typing with relation to the lower edge of the sheet.

It will be understood by those familar with this art that the totallength of spiral groove 29 must be directly related to the circumferenceof the platen, and to the standard length of the sheets of paper whichare normally to be used in the machine. If this invention is to beinstalled on a portable typewriter having a small diameter platen, thelength of groove 29 would be much greater than if the device was to beinstalled on a machine having a large diameter platen, assuming the samelength sheets of paper were to be used in both machines. Since the onlychange required is in groove length, the manufacturer will providedifferent plates 28 for different typewriters, and all such plates willbe interchangeable.

In offices using the same typewriter for typing on both eleven inch andfourteen inch sheets of paper, a slightly different embodiment of theinvention is provided. For such flexibility of use the length of thespiral groove 29 in plate 28 is made sufficient to take care of thefourteen inch paper, and a movable groove block 55 is provided toshorten the effective length of the groove when eleven inch paper is tohe used in the typewriter. Figs. 9 to 13 inclusive illustrate thismodified embodiment.

Referring to Fig. 10, it will be noted that spiral groove 59 is shownapproximately 270 longer than. the groove 29 in the Fig. 5 plate. Thisexcess in length will vary with the diameter of the platen to which thedevice is attached, and should be sufficient to allow the necessaryadditional platen rotation to accommodate the maximum length sheet ofpaper which is to be used in the typewriter. At a point corresponding tothe location of the inner end of groove 29, plate 58 is provided with aradially elongated recess 60, a portion of which intersects groove 59.Block 55 projects longitudinally into this axially disposed recess, andis movable radially therein to either block groove 59, and constitute astop at that point for the groove follower 24, or to clear the groove sothat the follower may travel freely to the extreme end of the groovebefore stopping plate rotation.

As a means of controlling the radial movement and position of block 55in its guiding recess 60, the outer end of block 55 is threadedlyconnected to one end of an elongated trigger 61 (Fig. 12), whichreciprocates longitudinally in a radial bore in boss 30 (Fig. 9) and aregistering perforation in retainer 32. The mentioned radial bore inboss 30 communicates with the outer end of recess 60, and is slightlylarger in diameter than trigger 61 to permit lateral movement thereofwithin the bore. Near its opposite and outer end trigger 61 is reducedin diameter as at 66 to form an annular shoulder 62. Just insideshoulder 62 the trigger body is provided with an annular groove 63 (Fig.13) which is adapted to tightly receive a U-shaped washer 64.

Referring to Fig. 11 it will be seen that a plate 65 is either madeintegral with or secured rigidly to the rim of plate 58. Plate 65 isprovided with a key hole type slot the larger portion 67 of which willfreely receive the larger diameter body portion of trigger 61. Thenarrow portion of this key hole slot will slidably receive the triggershank 66, but will not admit the larger diameter portion of the trigger.A push button 63 is threaded on the extreme outer end of trigger 61.

In assembling this groove block control, block 55 is first inserted inrecess 60. Trigger 61 is then inserted in the radial bore in boss 30,and is screwed tightly into the block 55. A coil spring 69 is thenslipped over the outer end of the trigger, compressed slightly, andwasher 64 is then slipped into its groove 63 to hold the springcompressed. Button 61 is then screwed on the outer end of the trigger.

By manually moving button 68 to the left in Fig. 11, shoulder 62 isaligned with slot portion 67, and spring 69 moves the trigger outwardthrough the slot until washer 64 contacts plate 65. Simultaneously block55 is moved radially outward and its inner end blocks groove 59. Withthe groove block in this position, the platen 16 is permitted to rotatea suflicient number of revolutions to accommodate the minimum lengthsheet of paper to be used.

When the maximum length paper is to be used, trigger 61 is moved inwardby pressure on button 68 until shoulder 62 moves beneath the lowersurface of plate 65. The button is then moved to the right in Fig. 11,causing shoulder 62 to pass beneath the narrow portion of the key holeslot. Plate 65 thus serves to temporarily maintain the trigger at theinner end of its permitted stroke, in which position groove block 55lies outside groove 59, and does not interfere with the travel of stop24 to the extreme inner end of the spiral groove.

It will thus be seen that the invention provides a simple attachment fortypewriters which will prevent the operator from typing too near thebottom of a sheet of paper, even though different sheet lengths are usedin the machine.

Having described the invention with sufiicient clarity to enable thosefamiliar with this art to construct and use it, I claim:

1. Pre-settable delayed action mechanism for arresting the rotation ofthe platen of a typewriter after the typing operation has caused theplaten to rotate through a selected number of degrees, comprising: ashaft connected to and extending axially from one end of the typewriterplaten; a plate mounted on and rotatable with said shaft in a planenormal to the shaft axis, said plate having a spiral groove in one sidesurface surrounding said shaft; and a groove following stop mounted onthe typewriter frame and projecting therefrom into the spiral groove insaid plate, whereby as the platen and plate rotate during the typingoperation and the end of the spiral groove contacts said stop, furtherrotation of the platen is prevented by such contact; a manually operableknob mounted on said shaft adjacent said plate; and means operablyconnecting the knob to said plate for moving the plate axially along theshaft away from said stop in response to slight rotation of the knob,for the purpose of unseating the stop from the spiral groove to releasethe platen.

2. Pre-settable delayed action mechanism for arresting the rotation ofthe platen of a typewriter after the typing operation has caused theplaten to rotate through a selected number of degrees, comprising: ashaft connected to and extending axially from one end of the typewriterplaten; a plate mounted concentrically on said shaft in a plane normalto the shaft axis, said plate having a spiral groove surrounding saidshaft in that side surface facing the typewriter; a grove following stopmovably mounted on the typewriter frame and projecting therefrom intothe spiral groove in said plate, said stop normally occupying a positionsubstantially normal to the grooved face of said plate, and movable in asubstantially radial direction only with relation thereto; a plateretracting member carried concentrically by said shaft adjacent theungrooved side surface of said plate; means connecting the plate to theretracting member for relative rotation; and means conmeeting the shaftto the plate and to the retracting member to cause all three to rotateas a unit when the shaft is rotated during typing, said last mentionedmeans being operable to move said plate axially along the shaft awayfrom said stop in response to rotation of the retracting member aboutsaid shaft.

3. The mechanism described in claim 2, and a housing rigidly secured tosaid retracting member and constituting a hand knob for rotating theretracting member.

4. The mechanism described in claim 2, and a compression coil spring onsaid shaft bearing against the outer end of said retracting member, andurging said retracting member and said grooved plate toward said stop.

Dair May 20, 1919 Larsen Feb. 21, 1922

